Developing Wicked Site! Stuck on Image Panning Action Script

Hi friends. i’m stuck on some AS and i need someone’s expertise.
Here’s a link to the site: http://www.invisioncreative.ca/v04/index2.html
Click on the top portfolio button and a portfolio section will slide in (load ext swf.)
I’ve used the code from http://www.kirupa.com/developer/flash8/interactive_image_pan.htm
The problem is I need to specify where the left and right edges of my scrollable area is - right now it is scrolling with regards to X = 0 and Y = 0. and the scrolling is way off.

Here’s the As from the portfolio scrolling movie: ( I’ve got the AS pasted on to a hot spot so it only works in that window - but the X and Y values are messed as you’ll see)

on (rollOver) {
this.onMouseMove = function() {
constrainedMove(bg_mc, 4, 1);
};
function constrainedMove(target:MovieClip, speed:Number, dir:Number) {
var mousePercent:Number = _xmouse/Stage.width;
var mSpeed:Number;
if (dir == 1) {
mSpeed = 1-mousePercent;
} else {
mSpeed = mousePercent;
}
target.destX = Math.round(-((target._width-Stage.width)mSpeed));
target.onEnterFrame = function() {
if (target._x == target.destX) {
delete target.onEnterFrame;
} else {
target._x += Math.ceil((target.destX-target._x)
(speed/100));
}
};
}
}
on (rollOut) {
this.onMouseMove = function() {
this.onMouseMove = false()
};
}

I totally appreciate any one who could point me in the right direction.
The Fla files are here: download portfolio.fla

http://www.invisioncreative.ca/source/